Investigation of nonlinear refraction and absorption in Mg- and Zr-doped LiNbO3with the aid of Z-scan techniques

Abstract

Using open-aperture (OA) and closed-aperture (CA) Z-scan techniques, the nonlinear absorption and refraction in pure, Mg- and Zr-doped congruent LiNbO3 crystals were evaluated with cw-laser beams. The CA Z-scan technique is used for a study of the strong nonlinearities including thermo-optical and photorefractive nonlinearity in LiNbO₃ crystals. Theoretical calculations together with the measurements make possible to characterize quantitatively the thermo-optical nonlinearity and to determine the threshold dopant concentration of the photorefractive damage which is very important for nonlinear optical applications.